Magneto-differential take-up mechanism



4March 11, 1958 c. F.4voN WEHRDEN 2,326,375

MAGNETO-DIFFERENTIAL TAKE-UP MECHANISM Filed Dec. 9, 1953 5 Sheets-Sheet1 J0 yJ2 MAG/V March 11, 1958 c. F. voN WEHRDEN Y 2,826,375 lMAGNETO-DIFFERENTIAL TAKE-UP MECHANISM Filed Dec. 9. 1953 l 5Sheets-Sheet 2 6.35 VT 2O@ j IL J2 50 7 c5] NoN-MA G/Vfr/c I N VEN TOR.mf/ F V072 M272 wen ATTORNEYS March 1l, 1958 c. F. voN wx-:HRDl-:N2,826,375

fummo-DIFFERENTIAL TAKE-UP MECHANISM Filed nec. '9. 1955 y ssheets-sheet s MAA/fr/c 75 1N VEN TOR.

Car/ Fran 0k/Uden A 770BNEY$ United States Patent O MAGNETO-DIFFERENTIALTAKEnUl NIECHANISM Carl F. von Wehrden, Honolulu, Territory of HawaiiApplicationDecember 9, 1953, Serial No. 397,277

7 Claims. (Cl. 242-7551) (Granted under Title 35,y U. S. Code (1952),sec. 266) The invention described herein may be manufactured and used byor for the Government for governmental purposes, without payment to meof any royalty thereon.

This invention relates to a mechanism for supplying a varying torque'from a xed torque source, and, more particularly, to a magnetodifferential take-up device which insures a constant rate of travel andapplication of a uniform tension to material being wound or reeled, suchas lilm, tape, thread, or wire. For example, in the winding and reeling.of m-oving picture lm with a sound track, the iilm must be wound at auniform rate for proper sound reproduction. When Winding film or othermaterial, the effective winding diameter of the film on the reel buildsup, resulting ina non-uniform winding rate which restrains the windingreel` from rotating at the proper speed. The device of the instantinvention drives the winding reel at an R. P. M.. sufficient to maintain:1 constant tension when the film is supplied to the winding reel at auniform rate of travel regardless of the winding diameter and otherfactors which would tend to vary the tension in the film.

Devices heretofore used to maintain constant tension in materialsupplied to a winding reel at a uniform lineal velocity have includedmagnetic brakes, friction clutches, slipping belts, and more recentlytorque motors. Generally, in winding. and reeling of material, controlof. lineal velocity and tension are obtained by braking means. Theinstant invention concern-s a tractive device rather than a restrainingdevice, as film or other material is fed to the reeling apparatus ratherthan being drawn from it, md the present construction. is in eiect asimplified version of a torque motor that is driven mechanically ratherthan by a source of external` electric power, and may be used inconjunction` with winding and reeling apparatus to maintain constanttension when material being wound or reeled is supplied to the reel at auniform lineal velocity. The instant invention was developed for use inconnection with ilm spool-drives, but may be applied to other materialbeing wound or reeled such as tape, thread, and wire, where constanttension for material supplied to a winding reel at a uniform rate oftravel is of paramount importance. Experience has indicated that torquemotors, while providing improved operation, for example, of film spooldrives, do not afford the constant tension that is essential with filmcarrying a sound track being reeled at a uniform lineal velocity toprovide proper sound reproduction. The devices presently in use do notentirely eliminate the difhculties resulting from improper tension suchas film damage, improper sound reproduction and Worn sprockets arisingfrom the use of the present troublesome friction devices. It istherefore a primary object of the present invention to provide animproved device for use in connection with winding and reeling equipmentwhich will maintain constant tension of material being wound or reeledcontinuously at uniform lineal velocity during the winding or reelingoperation.

It is a further object of the present invention to provide 2,826,375vPatented Mar. 1.1, s

ice

a device for maintaining constant tension of material being reeled at auniform lineal velocity wherein the device is controlled by the`difference of two speeds, one a constantl speed driven memberconstituting a part of the device and a variable speedl reeling member.

It is a further object of the present invention to pro vide adifferential'. gear train with an input element, an output element, anda magnetically controlled third element for maintaining constant tensionof material being reeled or wound at uniform lineal velocity.

It is a further object of the present invention to provide amagneto-diierential take-up device which docs not requirev adjustmentand does not depend on the use of friction surfaces or springs formaintaining constant tension of material being reeled or Wound atconstant lineal velocity.

lt is a further object of they present invention to providey a device.for continually maintaining uniformity of tensionof material beingreeled at constant lineal velocity, the operation` of which is notaffected by splashing lubricants, does not require frequent cleaning, isnot subject to rapid wear, and is simple to install.

It is a further object of the present invention to provide a device formaintaining constant tension of material being reeled at constant linealvelocity, which device ca-n be mounted co-axially with the reelingmember.

It is an additional object of the present invention to provide almagnetoediiferential take-up mechanism for maintaining constant tensionof material being reeled at constant lineal velocity wherein saidmechanism is not directly connected to an external electrical source andthe reel and. material being reeled are not common with said take-upmechanism.

It is a further object of the present invention to provide amagneto-dif`ferential take-up mechanism for reeling, operations whereinsaid take-up mechanism continuously applies a torque to the reelingapparatus which is proportional to the winding diameter of the reel fordriving said reel to maintain constant tension of the material beingreeled at constant lineal velocity.

It is a. still further object of the present invention to provide amagnetodiiferential take-up device for reeling apparatus wherein saidtake-up device applies a torque dierential, to said reeling apparatuswhich tends to drive the reeling apparatus at a speed of rotationsufticient to overcome the speed reduction incurred by the increasingwinding diameter of the reeled material and constantly maintain a speedof rotation of said reeling apparatus to insure constant tension of thematerial being reeled at constant lineal velocity.

Further objects and advantages will become apparent and the inventionwill be better understood from the following description taken inconnection with the accompanying drawings in which- Fig. 1 is a View inelevation of a particular embodiment of the instant invention showing amagneto-differential take-up mechanism employing one method ofdifferential gearing for connecting the driving source through amagnetic drive assembly to the reeling apparatus;

Fig. 2 is a partial left end elevational view of Fig. l;

Fig. 3 is a vertical sectional view taken on the line 3-3 of Fig. 2;

Fig. 4 is a vertical sectional View taken on the line 4 4 of Fig. 3;

Fig. 5 is a View partly in section of another embodiment of theinvention employing another form of differential gearing and coaxialarrangement of the magnetic drive assembly connecting the driving sourceto the reeling apparatus;

Fig. 6 is avertical sectional view taken on the line 3 6 6 of Fig. 5showing the differential gearing arrangement;

Fig. 7 is a vertical sectional view taken on the line 7-7 of Fig. 5showing the relative arrangement Iof the magnetic drive assemblycomponents;

Fig. 8 is a view, partly in section, of a further embodiment of theinvention wherein the driving source and magnetic drive assembly arecoaxially arranged with the driven reeling apparatus, and

Fig. 9 is a view, partly in section, of another embodiment of theinvention employing a differential gearing arrangement with externalcontact connecting the drive source to the reeling apparatus throughanother form of magnetic drive assembly.

Referring now to Fig. l, there is shown one embodiment of the instantinvention wherein the components constituting the magneto-differentialtake-up mechanism are mounted at one end of a shaft 1 supported in asleeve 2 which is in turn held by a support 3 of any convenient design.The sleeve 2 is prevented from rotating in the support 3 by set screws4. A collar 5 is secured by set screw 6 to the shaft 1 at the endopposite the take-up mechanism and prevents excessive lateral motion ofthe shaft. A reel or other similar winding member 7 to which material 7to be reeled is supplied at a uniform lineal velocity is also mounted onthe shaft 1 at the end opposite that mounting the take-up mechanismbetween the collar and a latch 8 which in cooperation with a springmember 9 retains the reel or winding member 7 in position on theshaft 1. A combination of a pulley 11 and internal gear 12 formedintegrally therewith is arranged for free rotation on shaft 1. A torquearm 13 eccentrically mounted is secured to shaft 1 by means of a setscrew 14 adjacent to the internal gear portion of the combined pulleyand internal gear struct 1'e. The arm 13 has formed integral therewithat one outermost end a portion which is upstanding with relation to theplane of the arm 13, which portion has a bore 15 therethrough at rightangles to the plane of the arm 13 for receiving a shaft 16 which isparallel to shaft 1. The shaft 16 which protrudes beyond the bore 15 hasa pinion gear 17 secured at one end thereof for contact with theinternal gear 12. The opposite end of the shaft 16 which also protrudesbeyond the bore 15 carries a mounting plate 18 having mounting studs 19located on the outer plane surface thereof. A cup-shaped member 20 ofnon-ferrous metal such as aluminum, having a central aperture 21 andapertures 22 mutually spaced from the central aperture 21,

arranged for registering relation with the aforesaid A mounting studs19, is secured to the mounting plate 18 by seating on the studs 19 andbolt 23 engaging an internally threaded portion in the outer end of theshaft 16 and coaxial therewith. Two L-shaped permanent magnet members24, 2S are also secured by the shorter legs of the L-shaped members tothe arm 13 as by bolts 27, so as to provide an air gap 26 between thelonger legs of the L- shaped members which are parallel to the plane ofthe arm 13. When so mounted, a portion of the arm 13 forms a yoke forthe permanent magnet members. The opstanding portion of the cup-shapedmember 20 is arranged to pass through the magnetic field in the air gap26 when the cup-shaped member is rotated.

When the device is operating, the pulley 11 and the integral internalgear 12, which combination is free to rotate on shaft 1, are driven atconstant speed from au external source. Internal gear 12 meshes withpinion gear 17 which is connected through the shaft 16 to the cup-shapedmember 20. If no retarding torque is applied to the shaft 16 by thecup-shaped member 20, pinion gear 17, shaft 16, and the cup-shapedmember 2) rotate in a xed position in accordance With the ratio ofinternal gear 12 and pinion gear 17. However, since the non-ferrouscup-shaped member 20 passes through the magnetic iield in air gap 26between the permanent magthe retarding torque applied to shaft 16 bycup-shaped member Zi?. Rotation of pinion gear 17 along internal gear 12causes the shaft 1 to be rotated by rotational force applied by the arm13 which revolves about a lungi-- tudinal axis through shaft 1 to whichthe arm 13 is secured.. Since the arm 13 is fastened to the shaft 1,rotational If a re tarding force suiiicient to stop the cup-shapedmember force is applied to the reel 7 attached thereto.

26 were applied by virtue of the opposing magnetic field resulting fromthe self-generated eddy currents, shaft 16 and pinion gear 17 would beprevented from rotating about the axis of shaft 16, and being thusrestrained in a fixed meshed position, pinion gear 17 and arm 13 wouldbe rotated at the same speed as the pulley 11 and integral internal gear12. Reel 7 connected to arm 13 through shaft 1 would therefore alsorotate at the same speed as the combination of pulley 11 and internalgear 12. In the practical application of the instant invention, the arm13 is restrained from rotating as fast as the assembly of pulley 11 andinternal gear 12 by the lm or other material 7' being reeled. The arm 13thus rotates at a lower lineal velocity than that of a point on thepitch diameter of internal gear 12. The speed of rotation of thecombined assembly of pulley 11 and internal gear 12, which is constant,must be greater than the maximum speed of shaft 1 and the parts attachedthereto to overcome the friction of the moving parts which occurs at theminimum winding diameter of the material being spooled. There is alwaysan overdrive and this speed differential increases as the windingdiameter increases and the reel 7 slows down. The speed of the shaft 1will therefore be controlled by the speed and effective winding diameterof the material 7 on the reel 7 carried by the shaft 1. As the reel 7iills with material 7, at a constant lineal velocity, the effectivewinding diameter will increase and the rotation speed of shaft 1 and arm13, attached thereto, will slow down, causing an increase in the speedof pinion gear 17 and cup-shaped member 20. The increased speed ofrotation of the cup-shaped member 20 through the linx in the magneticair gap 26 increases the eddy currents generated therein andconsequently greater opposition to the magnetic eld in the permanentmagnet structure results, tending to retard the rotation of the member20, which in turn causes increased torque to be exerted on arm 13 andshaft 1 in a manner previously described, which increase in torque isrequired to balance the longer lever arm of the material 7 at the largerwinding diameter on the reel 7 on shaft 1. The increase in speed ofmember 20 and consequent increase in torque is proportional to theincrease in winding diameter of material 7', and consequently constanttension will result for the winding of an entire reel of material.

The structure shown in Fig. 5 operates on the same principle as thestructure shown in Figs. 1 and 3 but is a more compact coaxialarrangement employing another form of differential gearing and permanentmagnet structure, a portion of which serves as an end closure for theunit. The shaft 1 and reel 7 are supported in the same manner as shownfor the embodiment illustrated in Figs. l and 3. The combined assemblyof pulley 11 and internal gear 12 has a slightly different configurationand includes a portion 28 which joins the pulley 11 to the internal gear12 and forms a cavity 29. A circular band 30 of non-magnetic material issecured to a portion of the exterior surface of the combined assembly ofpulley 11 and internal gear 12 by bolts 31 so as to form an extensionthereof which is iiush with the exterior surface of the combinedassembly and coaxial with the shaft 1. A cup-shaped permanent magnetstructure 32 having an upstandiug portion 33 located centrally of thebight portion thereof, is joined to the combined assembly of pulley 11and internal gear 12 by the circular band 30 by bolts 31 with the angeof the cup-shaped magnet member facing the combined assembly so that thepermanent magnet structure 32 forms a closure for the unit. A cruci-formpole member 34 of permanent magnetic material is integral with theupstanding portion 33, at right angles thereto, with the flange of thecup-shaped magnet structure 32 surrounding the arms of the cruciformpole member 34. The arms of the member 34 are slightly shorter in lengththan the diameter of the Hange so as to form an air gap 35 therebetween.An arm 36 is eccentrically secured to shaft 1 and positioned within thecavity 29. The arm 36 has an aperture 78 therethrough in a -direction atright angles to the length of the arm to receive a stub shaft 37 securedby set screw 38 which extends for a distance in the direction of theinternal gear 12 sufcient to permit mounting a planet gear 39 by meansof a bolt and washer assembly 45 so as to mesh with internal gear 12. Acup-shaped member 40, having a central tubular portion 41 integraltherewith -for slip-fitting on the shaft 1 is secured thereto adjacentto the end thereof extending toward the cruciform member 34- by bolt 4.2and Washer 43 in such manner that the upturned portion of the cup-shapedmember 40 may pass through the air gap 35. The cup-shaped member di) isconnected to the planet gear 39 through a sun gear 44 carried by shaft 1'between the arm 36 and cup-shaped member di). Sun gear 44 may beseparate or integral with cup-shaped member 40.

The operating principle of the modification shown in Figs. 5, 6 and 7 issimilar to that shown in Figs. 1, 2, 3 and 4. When the combined assemblyof pulley 11, internal gear 12 and the permanent magnet assembly mountedfor free rotation on shaft 1, are driven by an external source and theshaft 1 is restrained from rotating, the planetgear 39 will revolve andin turn rotate the sun gear 44 and the cup-shaped member 40 through themagnetic held in the air gap 35. The opposing magnetic field set up bythe eddy currents thus generated in the cup-shaped member 40 will retardthe rotation of member 413, sun gear 44 and planet gear 39 causing atorque to be applied to the arm 36. The torque so developed will varywith the speed at which shaft 1 is allowed to rotate. For example, whenshaft 1 is prevented from rotating, maximum torque is developed, andwhen the revolutions per minute of shaft 1 equal the revolutions of thecombined assembly of pulley 11 and internal gear 12, no torque will bedeveloped. For intermediate values of revolutions per minute of shaft 1,the amount of torque developed will be in proportion to the differencein speeds of shaft 1 and the combined assembly of pulley 11, internalgear 12 and the permanent magnet assembly. The speed of shaft 1 iscontrolled by the lineal speed of the material 7 being spooled and thewinding diameter. The difference in speeds between the combined assemblyand shaft 1 is multiplied by the gear train or other mechanicalequivalents vsuch as sprockets and chains and rubber drive wheels torotate the cup-shaped member 4t) through the magnetic field atsuiiicient speed to produce the necessary torque driving shaft 1 toproduce the required tension in the material 7' being spooled.

The modification shown in Figs. 5, 6, and 7 is likewise applicable towinding material such as tape, film, wire, and thread at constanttension and uses the variation in winding diameter of the material 7 toregulate the change in torque necessary to provide constant tension forthe material being reeled at uniform lineal velocity.

There is illustrated in Fig. 8 a further embodiment of the device of theinstant invention` wherein the components are coaxially arranged andthe. relative position ofthe combined'internal gear and pulley, and thepennanent magnet and cup-shaped non-magnetic member are reversed. Inthis arangement the unit is composed of individual separate componentsand the cup-shaped nonmagnetic member forms the end closure member forthe unit. The support for the unit and the reel is similar to thatillustrated in the previous embodiments and are designated bycorresponding reference numbers. A pulley 45 is carried by shaft 1 forfree rotation thereon at the end opposite the reel 7 and adjacent thesleeve 2. A circular band 3D similar to that used in the embodimentillustrated in Fig. 5 joins the pulley 45 and a cup-shaped permanentmagnet structure 46 in mutually spaced relation. The magnet structure 46has an aperture 47 centrally located on the bight portion thereof andupstanding portions 48 located intermediate the ange 49 of saidcup-shaped member and said central aperture 47. A permanent magnet polemember 50, which may be any convenient shape, is secured to theupstanding portions 48 by bolts 50'. The magnet member 50 is slightlyless in length than the diameter of the flange 49 thereby providing anair gap 51 in the magnetic circuit. The pole member 50 has a centralaperture 57. A cup-shaped member 54,` the vertical side portions ofwhich form an internal gear 52, is arranged intermediate the pulley 45and permanent magnet structure 46 with the internal gear facing thepulley and forming a cavity 53 therebetween. The cup-shaped member 54has a central aperture 56 and is secured by bolts 55 through the basethereof to the bight portion of the permanent magnet structure 46. Thepulley 45, internal gear 54 and permanent magnet structure 46 are of thesame diameter and the apertures 47, 56, and 57 are axially aligned andcoincident with the longitudinal axis of shaft 1. A shaft 58 passesthrough the aligned apertures 47, 56, and 57 and protrudes beyond theapertures 56 and S7 to permit mounting a sun gear 59 on the end withinthe cavity 53 and a mounting plate 60 on the end protruding beyond theaperture 57. The mounting plate 60 has a central aperture 61 and aplurality of mounting studs 62 surrounding the central aperture 61 andmutually spaced therefrom. A cup-shaped non-mag'- netic member 63 havinga central aperture 64 surrounded by mutually spaced apertures 65 whichare in registering relation with the mounting studs 62, is mountedthereon and secured to the shaft 58 by aV bolt 66 so that the upstandingportion of the cup is free to rotate through the magnetic field in airgap 51. An arm 67 is eccentrically secured to the shaft 1 within theportion of the cavity 53 formed by pulley 45. The arm 67 has an aperture63 therethrough in a direction at right angles to the length of the armto receive a stub shaft 69 secured by set screw 70. The stub shaft 69extends toward the internal gear S2 an amount sufficient to permitmounting a planet gear 71 by bolt and washer assembly 72 for meshingrelation with the internal gear 52. Sun gear 59, carried lby shaft 58,meshes with planet gear 71.

The operation of the modified formV of the invention illustrated in Fig.8 is similar in principle to that of the previously described forms. Anexternal drive source connected to pulley 45 rotates the combinedassembly of pulley 45, internal gear 52 and the entire permanent magnetassembly freely on shaft 1. Rotation of the internal gear 52 causesplanet gear 71 to be rotated which in turn drives the sun gear 59 andthe cup-shaped nonmagne'tic member 63, carried on the same shaft 58,through the magnetic field existing in the air gap 51. The differentialgearing arrangement provides relative rotation between the combinationof pulley 45, internal gear 52, the complete permanent magnet assemblyand the nonmagnetic cup-shaped member 63 which rotates at a highervelocity relative to the combined pulley, internal gear and permanentmagnet assembly. Rotation of the cupshaped member 63 through themagnetic eld in the air gap 51 induces eddy currents in the cup-shapedmember, retarding the rotation thereof as previously explained, which inturn results in the application of a torque to the arm 67 and throughshaft 1 to the reel 7 which results in constant tension of the material7 being reeled at uniform lineal velocity. The torque developed will beiin proportion to the difference in speeds of shaft 1 and y'combinationof pulley, internal gear and permanent magnet assembly. Thesamerelations exist with regard to winding diameter, speed of shaft l,lineal velocity of material 7 being spooled and speed of the combinedassembly of pulley and internal gear, differential gearing, cup-shapedmember and permanent magnet assembly for the modification illustrated inFig. 8 as for the forms of the invention previously described.

A further modiiication of the invention is illustrated in Fig. 9 whichdiffers from the previous forms in that an external gear and permanentmagnet structure is used wherein the torque arm is a part of thepermanent magnet structure. The support structure for the formillustrated in Fig. 9 is similar to that used in the embodimentspreviously described and corresponding parts have been designated bylike reference characters. A pulley 73, having combined therewith in anintegral structure an external gear '74, is mounted for free rotation ouone end of the shaft 75 which extends beyond the support sleeve 2.Mounted on the same end of shaft 75 on the outer end portion thereof andadjacent the combination of pulley 73 and external gear 74 is a U-shapedmember 76 formed from sheet material, having legs of unequal length. Acup-shaped permanent magnet 97 having a central upstanding portion 77 issecured by any convenient means to the internal side of the longer leg79 of the U-shaped member 76. The central upstanding portion 77 has abore 80 longitudinally thereof and the longer leg 79 of the U-shapedmember 76 is provided with an aperture 81 in registering relation withthe bore Si) for securing the combination of U-shaped member andcupshaped lpermanent magnet structure 97 on shaft 75 by a set screw 82.Secured to the inside surface of the shorter outside leg 83 of theU-shaped member 76 by any convenient means is a permanent magnet member84, which being mutually spaced from the cup-shaped permanent magnetstructure forms an air gap 85 therewith. The longer leg 79 of theU-shaped member 76 has an upstanding portion 98 of substantial diameterfacing inwardly of the leg 79 with a bore 86 therethrough. The axis ifthe bore 86 is at right angles to the plane of the longer leg 79 andparallel to the axis of the shaft 75. A stub shaft S7 is carried withinthe bore 86 and extends a distance beyond each end of the bore to permitmounting a pinion gear 88 at the end adjacent the external gear 74 inmeshing relation therewith and a mounting hub 89 having a central bore90 for mounting on said stub shaft 87 at the end opposite said piniongear 88. A plurality of mounting studs 91 protruding beyond the outerplanar surface of the mounting hub are arranged in surrounding mutuallyspaced relation from said central bore 90. The stub shaft S7 has aninternally threaded, longitudinal recess 96 centrally located. A disk 92of non-magnetic material having a central aperture 93 and surroundingadjacent mutually spaced apertures 94 in registering relation with saidprotruding studs 91 for mounting said disc 92 on stub shaft 87. The discis further held in position on stub shaft 87 by a bolt 9S engaging theinternally threaded recess 96. The disc 92 is of suiicient diameter toinsure passing through the magnetic field in the air gap 85 between themutually spaced permanent magnet members of the magnetic circuit.

The operation of the embodiment shown in Fig. 9 is also similar inprinciple to the embodiments previously described. An external drivesource is connected to the combination pulley 73 and external gear 74thereby rotating the pulley which in turn drives pinion gear 88 and disc92. As the disc 92 is rotated through the magnetic ux in the air gap 85,eddy currents are induced therein which tend to retard the disc causinga torque, proportional to the difference in speeds of shaft '75 andcombination assembly of pulley 73 and external gear 74, to be applied tothe shaft 75 and reel 7 attached thereto by a latch 8 which incooperation with a spring member 9 retains the reel or winding member 7in position on shaft 1 The torque arm in this embodiment is the longerleg 79 of the U-shaped member 75. The same relations with regard towinding diameter, speed of shaft 75, lineal velocity of material 7'being spooled and speed of the combined assembly of pulley, externalgear, permanent magnet and attached U-shaped member for the embodimentillustrated in Fig. 9 as for the preceding embodiments.

From the foregoing description it is evident that the instant inventionprovides a simple, compact structure employing a principle of operationwhich insures constant tension for material such as tape, thread, wire,and lm being reeled at uniform lineal velocity wherein the tension iscontrolled by the material being reeled. The principle involved may beapplied in a Variety of embodiments of which those described arerepresentative.

Having thus described my invention, what I claim as new and wish tosecure by Letters Patent is:

l. A magneto-dilerential take-up assembly for reeling apparatuscomprising support means, a shaft carried by said support means for freerotation therein, said shaft extending in opposite directions beyondsaid support means, a reel, an input element, said reel mounted in fixedposition on an extending end of said shaft, said input element mountedfor free rotation on said shaft in mutually spaced relation with saidreel, eddy current generating means, differential drive means connectedto said input element, torque applying means secured to said shaft andcoupling said eddy current generating means to said differential drivemeans whereby upon retardation of said eddy current generating meansresponsive to variations in velocity of said shaft relative to saidinput element force is applied to through said torque applying means tosaid shaft effective to maintain constant tension in material beingwound on said reel at uniform lineal velocity.

2. A magneto-differential take-up assembly for reeling apparatuscomprising support means, a main shaft carried by said support means forfree rotation therein, said main shaft extending in opposite directionsbeyond said ysupport means, a reel secured to one extending end of saidmain shaft, a pulley mounted for free rotation on said main shaft inmutually spaced relation with said reel, an internal gear integral withsaid pulley, a torque arm secured to said main shaft adjacent saidinternal gear in face relation therewith, a pinion gear, a stub shaftcarried by said torque arm parallel to said main shaft, said pinion gearsecured to said stub shaft for maintaining said pinion gear in meshingrelation With said internal gear, a pair of elongated permanent magnetmembers secured to said torque arm and extending in a direction parallelto the length of said torque arm, said magnet mem'bers arranged inmutually spaced relation to form a magnetic path, a non-magneticcup-shaped member secured to said stub shaft to permit rotation throughsaid magnetic path, said pulley, torque arm, permanent magnet membersand cup-shaped member arranged in lateral mutually spaced relation withsaid cup-shaped member and cooperating to apply a force to said torquearm dependent upon the velocity of said pulley relative to saidcup-shaped member whereby said main shaft and attached reel -are drivento maintain constant tension of material being reeled at uniform linealvelocity when said pulley is driven at constant velocity. Y

3. In vcombination with a reeling apparatus, a magnetodierential take-upmechanism for maintaining constant tension Vof material being reeled atuniform lineal velocity comprising `a support, a main shaft carriedbyfsaid support for free rotation therein, said main shaft extending inopposite directions beyond said support, pulley means mounted for freerotation on one extending end of said main shaft, internal gear meansformed integral with said pulley means, cup-shaped permanent magnetmeans having a planar base portion, means connecting said permanentmagnet means to said pulley and internal gear means in coaxialregistering relation, said cup-shaped magnet means having a centralportion perpendicular to the planar base portion thereof, a magneticpole structure formed integral with said perpendicular portion at rightangles thereto within said cup-shaped magnet means, said pole structurebeing of lesser diameter than said cupshaped magnet member therebyforming a magnetic field therebetween, said cup-shaped magnet means andsaid pulley means being mutually spaced to provide a cavitytherebetween, said pulley means and said cup-shaped magnet meanscooperating to form closure means for said mechanism, torque applyingmeans secured to said main shaft within the portion of the cavity formedby said pulley means, a stub shaft carried by said torque applyingmeans, a planet gea-r carried by said stub shaft for meshing relationwith said internal gear means, a sun gear mounted on said main shaft inmeshing relation with said planet gear, a cup-shaped non-magnetic membercarried on said main shaft for rotation through said magnetic field andresponsive to variations in velocity of said main shaft wherebyretardation of said cup-shaped non-magnetic member relative to saidpulley means applies a force to said torque applying means through saidplanet and sun gears for rotating said main shaft to maintain constanttension in material being reeled at uniform lineal velocity when saidpulley means is driven at constant velocity.

4. A magneto-diierential torque motor for maintaining constant tensionof material being reeled at uniform lineal velocity, comprising asupport, a main shaft carried by said support for free rotation therein,said main shaft extending in opposite directions beyond said support,means externally driven and mounted for free rotation on said main shaft`on one extending end of said main shaft, a cup-shaped permanent magnetstructure having a planar base portion and a ange portion perpendicularthereto, means connecting said externally driven means to the planarbase portion of said cup-shaped permanent magnet structure in mutuallyspaced coaxial registering relation, a differential gear train assemblylocated between said externally driven means and said cup-shapedpermanent magnet structure and secured to said permanent magnetstructure for cooperative simultaneous rotation therewith, a secondshaft, said cup-shaped permanent magnet structure having a centralaperture, an upstanding portion located intermediate the ange portion ofsaid cup-shaped magnet structure and said central aperture, a pole piececarried by said upstanding portion positioned within the ange of -saidcup-shaped magnet structure adjacent the outer rim thereof, said polepiece being of lesser diameter than said cup-shaped magnet structureforming a magnetic path therebetween, said pole piece and saiddifferential gear train assembly each having a central aperture inregistering relation with the central aperture in said cup-shaped magnetstructure to receive said second shaft in longitudinal coaxial alignmentwith said main shaft, a cup-shaped non-magnetic member carried by saidsecond shaft for rotation through said magnetic path, torque applyingmeans secured to said main shaft and coupled to said cup-shapednon-magnetic member through said differential gear train assembly forrelative rotation therewith, said cup-shaped non-magnetic memberresponding to variations in velocity of said main shaft relative to saidexternally driven means, whereby retardation of said cup-shapednon-magnetic member im- 10 poses a force on said torque applying meansthrough said dierential gear train assembly to said main shaft tomaintain constant tension of material being reeled at uniform linealvelocity when said externally driven means is rotated at constantvelocity.

5. A magneto-differential torque motor for maintaining constant tensionof material being reeled at uniform lineal velocity, comprising asupport, a main shaft carried by said support for free rotation therein,said main shaft extending in `opposite directions beyond said support,pulley means carried by said main shaft for free rotation thereon,external gear means integral with said pulley means and in lateralcoaxial relation therewith, a U- shaped member having legs of unequallength and substantial width, the longer leg of said U-shaped memberbeing apertured to permit supporting said U-shaped member on said mainshaft in adjacent relation to said external gear, a cup-shaped permanentmagnet structure having a central upstanding portion secured to theinner side of the longer leg of said U-shaped member and adapted to besupported by said main shaft in fixed relation thereto, the shorter leg-of said U-shaped member being free of said main shaft and arranged inmutually spaced face relation with said cup-shaped magnet structure, adisc-shaped permanent magnet structure secured to the internal surfaceof the shorter leg of said U-shaped member in mutually spaced facerelation with said cupshaped magnet structure forming a magnetic paththerebetween, an upstanding portion having a bore therethrough formedintegral with the longer leg of said U- shaped member adjacent the endthereof and perpendicular thereto, a stub shaft carried within said boreparallel to said main shaft and extending a substantial distance beyondsaid bore, a pinion gear carried by said stub shaft in meshing relationwith said external gear, a non-magnetic disc carried by said stub shaftin opposed relation to said pinion gear for rotation through saidmagnetic path, said disc being responsive to variations in velocity ofsaid main shaft relative to said pulley means whereby retardation ofsaid disc imposes a force on the longer leg of said U-shaped membereffective to rotate said main shaft to maintain constant tension ofmaterial being reeled at uniform lineal velocity when said pulley meansis driven at constant velocity.

6. A device for regulating 'reeling apparatus to maintain constanttension of material being reeled at uniform lineal velocity comprising ashaft, support means for said shaft, input means mounted for freerotation on said shaft, said input means being driven at constantangular velocity, a reel mounted adjacent an end of said shaft forrotation therewith and remote from said input means, an armeccentrically secured to said shaft adjacent said input means forrotation in a plane normal to the axis of said shaft, mechanicalcoupling means enacting with said arm and interconnecting said inputmeans and said shaft, permanent magnet means including an air gapmounted for rotation about said shaft adjacent said input means andelectrical conducting means connected to said mechanical coupling meansand rotated through said air gap upon rotation of said input means,rotation of said conducting means through said air gap inducing eddycurrents therein opposing the magnetic flux in said air gap andretarding the rotation of said conducting means whereby a varying torqueis applied through said arm to said shaft to maintain uniform tensionwith varying winding diameter of material wound on said reel at constantlineal velocity.

7. A device for maintaining constant tension in material being reeled atuniform lineal velocity comprising a shaft, support means for saidshaft, input means mounted for free rotation on said shaft, said inputmeans being driven at constant velocity, a reel mounted adjacent an endof said shaft for rotation therewith and remote from said input means,an arm eccentrically secured to said shaft adjacent said input means forrotation in a plane l1 normal to the axis of said shaft, differentialdrive means coacting with said arm and interconnecting said input meansand said shaft, said dierential drive means and said shaft havin y acommon center of rotation, permanent magnet means including an air gapsupported coaxially by said input means for free rotation about saidshaft, electrical conducting means supported by said shaft for rotationthrough said air gap simultaneously upon rotation of said input means,rotation of said conducting means through said air gap inducing eddycurrents therein opposing the magnetic ux in said air gap and retarding'the rotation of said conducting means, said electrical conducting meansconnected to said arm through said diiferential `drive means, wherebyupon rotation of said dilerential drive means about its center ofrotation, due to variations in angular velocity of said reel relative tosaid input means, a varying torque is applied through said arm to saidshaft to maintain uniform tension with varying winding diameter ofmaterial wound on said reel at constant lineal velocity.

References Cited in the tile of this patent UNITED STATES PATENTS

